Apparatus for deposition of dry fibers int the manufacture of fibrous structures



X Aug. 9, 1955 J. DA. CLARK ET AL APPARATUS FOR DEPOSITION OF DRY FIBERSIN THE MANUFACTURE OF FIBROUS STRUCTURES 2 Filed July so, 1955 IN VENTOR. %m dmfim W 3y I 3 1% 1M,

ATTORNEYS.

United States Patent O APPARATUS FOR DEPOSITION OF DRY FIBERS IN THEMANUFACTURE OF FIBROUS STRUC- TURES James DA. Clark, Longview, Wash.,and Bror E. Anderson, Park Ridge, 111., assignors to A. B. Dick Company,Niles, 111., a corporation of Illinois Application July 30, 1953, SerialNo. 371,258

3 Claims. (Cl. 19-156) This invention relates to the air deposition ofdry fibers in the manufacture of fibrous structures such as continuous,nonwoven webs and fabrics formed of fibrous elements, such as separatedfibers or wafers, and it relates more particularly to an improvement inthe apparatus for the manufacture of fibrous structures which isdescribed in my copending application Ser. No. 313,316, filed on October6, 1952.

Briefly described, the method and apparatus of the aforementionedcopending application embodies the use of an elongate cylindricalhousing having one or more inlet openings in the upper end through whichfibers are introduced and which has a foraminous separating Wall in aspaced portion thereof through which fibers entrained in a stream of airare carried through the separating wall for substantially linear flow toa collecting wall spaced a short distance below the foraminousseparating wall and upon which the fibers are deposited in aninterfelted relation. The collecting wall may be foraminous to enableair to be withdrawn from the underside for holding the deposited fibersonto the surface thereof and the amount of air withdrawn through thecollecting wall is preferably adapted to be greater than the amountpassing through the foramens of the separating wall so that air willflow slowly from the surrounding atmosphere into the space between theseparating wall and the collecting wall but in amounts incapable ofinterfering with the linear flow of fibers. By the balancing of the airflow as described, an apparatus may be supplied which for the first timepermits the area between the separating wall and the collecting wall toremain open to the atmosphere without blowing fibers out into the room.

The entrainment of fibers in the air stream within the housing and thesubsequent passage of substantially uniformly controlled volumes of airand fibers from the r housing through the openings of the separatingWall to the collecting Wall is achieved by an air scrabbler in whichstreams of air at high velocity are introduced tangentially into thehousing to cause the air and the fibers therein to circulate rapidly inone direction about the housing. This causes the fibers within thehousing to become entrained within the air stream. The circulating airand entrained fibers, of which there is always an excess available, overthe face of the separating wall and under positive pressure, not onlykeeps the openings in the wall substantially free of clogging fibers butbecause of the pressure, resulting from the excess of both air andfibers, generates a shower head eifect which results in the passage ofequal volumes of both air and entrained fibers through each of theopenings of the separating wall to the collecting wall. The volume ofair and fibers passing through the separating wall in response to theshower head effect constitutes a relatively small proportion of air andfibers circulating within the housing.

It is an object of this invention to provide improvements in the methodand apparatus for the air deposition of dry fibers in the manufacture offibrous struc tures and it is a related object to provide a method andapparatus for the air deposition of dry fibers using a fiber depositinghead based upon an air scrabbler in which means are provided forreducing fiber agglomeration and maintaining fiber separation anddistribution for the passage of uniform volumes of fiber through theforamens of the separating wall and the formulation of a fibrousstructure having a uniform distribution of fibers on the collectingwall; and in which a minimum number of fiber bundles are formed tointerfere with the smooth and uniform transfer of fibers from Within thehousing to the collecting wall or deposit undesirable bundles of fibersin the web which is formed on the collecting wall.

These and other objects and advantages of the invention will hereinafterappear and for purposes of illustration, but not of limitation,embodiments of the invention are shown in the accompanying drawing inwhich:

Figure 1 is a schematic view in sectional elevation showing a fiberdepositing head embodying features of this invention;

Figure 2 is a sectional view taken substantially along the line 2-2 ofFigure 1.

It has been found that a uniform distribution of fibers in the airstream within the housing may be secured and agglomeration of fibersinto bundles may be lessened when some of the air streams are introducedinto the housing at angles varying from tangential, as before, to radialwith at least some of the jets introducing streams of air in asubstantially radial direction into the housing while most of the jetscontinue to be introduced substantially tangentially.

The fiber depositing head in which the concept of this invention hasprimary application comprises a cylindrical housing 10 which may be ofvariable width depending upon the width of the fabric to be formed. In aunit of medium capacity, the housing 10 may be 1 /2 feet in diameter and4 feet in width. A feed opening 11 extends practically completely acrossthe upper portion of the housing in communication with a feed duct 12through which fibrous elements 13 in the form of sparated fibers ofwood, cellulose, synthetic fibers, mineral fibers or pulp fibers, orfibrous elements of substantial dimension, such as thin wafers or cutstrands, may be fed, preferably at a continuous and constant rate intothe housing.

A foraminous separating wall 14 is provided in the lower portion of thehousing through which fibrous elements entrained in air pass on theirway towards a collecting wall 15 upon which the fibers are separated ininterfelted relation to form a web 16 on the surface thereof. Theforaminous separating wall may constitute a separable foraminous membersecured in position across an opening 17 Within the housing in a mannerto permit exchange so that the type of openings or an arrangement ofopenings 18 best suited for particular fibers may be used for mostefiicient production. The openings in the separating Wall may comprise aplurality of spaced apart apertures controlled as to size and spacingfor particular fibrous elements as described in the copendingapplication Ser. No. 61,674, or the openings maye be in the form of oneor more continuous slots extending across the housing incircumferentially spaced apart relation, as described in the copendingapplication Ser. No. 313,316.

The collecting wall 15 is preferably formed of an end-. less screenadapted to be advanced in one direction con tinuously across the areabeneath the foraminous separating Wall 14 or it may be in the form of aseries of caul';

plates upon which the fibrous elements are deposited topro'ducesaniinterfelte'd :structure for molding into panels while on.the, owl, plates. .The .foraminous ..collecting vwall which is preferredin the manufacture of webs of separated fibers, as shown, is supportedupon a rigid surface 19 havingzlanr opening izflrinzthe areallyingnbeneath: the separratzingrwlall. :AssuctionrboxflL isaprovide'd:in;cornmunica- ..-tiona :withrth opening; andsservesizforznseinuwith'drawing' .a ItMOlUIIICHOfJZZlI'ifIQm the: underside rof the.icollectionwwall which. atilleastiequalztto andepreferably: larger than.the Molume: f air-,which-upasses'with the'fibersthroughthe:separatingmvall with the resultthat .the. deficiency is made supbbyzassl-ight .in'flow :of .-'.air .into :the space. between theaseparatingtwall and-the collectingv walli from the.surroundjngzatmosphere. when thiscdifference in air volumesis :small;the::inflow:of= -airwis;of such;character .as not to-inter- :tferevwith: therz'substantially' linearsmovement of the fibers fromitheaseparating .rwall toithelcollecting wall withthe resultrthatithefiber;depositing areamanlbe allowed to'remain open to the atmospherewithout disturbingthe distributionszofcfiberssand without loss of'fibersinto the atmosphere.

iuMarkedtimprovementshave:been foundto result with respect ate 3 the.distribution and separation. of the fibers within the housing when,instead of introducing all of the rairsstreamsitangentially into thehousing, some oftheair streams are introduced radially While others areintroduced at angles therebetween, although such inbetween jetsaresnotmecessary. IIt is.-best rwhenzthegreatestnumber of inlets arepositioned to introduceathe streamstangentially whilmfewerrare spacedacross'the housing and positioned torintroduee the;streamsaradially,:while possibly still a few others arepositionedztointro duce' the airstreams at angles therebetween.

:Oner satisfactory "arrangement is illustrated in the drawings' whereeleven inletszareillustrated as extending across therhousing.zTheifirst, third, fifth, seventh, ninth and eleventhirilets: indicatedby the letter -T .are positioned to introduce the streams .sof i'highvelocity -air tangentially into: theihousiug. 'xThe'fourth and eighth,indicated by the letter Reareapositionedito introduce the streams of-airradially. into .the:housing,. and. thC'-S6CO1'ld,SiXth and tenthinlets,.indicated by the letter A, arepositionedtointrodUCfiJIhfilIFStI'CfiIIIS of. air at:an..angle between radial andtangential.

:In:. theory,:it..is believed that. the tangential streams'ofairsintroduced: into "the: housing: impart the forces forcircula'ting:movement of the air and fibers'about the housing to;providei.the=layer-which moves constantly under positive pressure.:across:theforamens'of the separating wall and from which a-smallspropor'tionentrained in air'peels off fortpassagewith the. air through thejforamens.of' theseparating wall to the collecting wall. While the radial streamsofn-airlintroduced into 'the housing would seem to interfere with.this'circulatingmovement,-they, in fact, do not impartsuch.interferencertand instead appear to improve the entrainment-and thedistribution of the fibers -in the circulating streams of. air withtheresult that fiber clumping iszmarkedlyareduced as compared'to thatwhich exists in therabsence ofsuch:radial'streams. Because ofthe greaterdegreerofsseparat ion and reduced clumping, theproductioniiof:a'moreiuniform -layer ofseparated fibers is securedwithrless interference and interruptions to keep the foramensof theseparating' wall clear for passage of uniform volumes of airand fiberstherethrough.

:Thesainstreams:introducedatangles between radial andtangentialrarernotsalways necessary but they assist both in::circulatingthe air and fibers about the housing over the separatinggyallandmaintaining more complete fiber separationrandz'distribution. Themoreimportant function of the inbetweeninlets -.is:to-impinge upon theface of the separating wall and thereby assist-in the removalofanyfiberstwhichvmight become entrapped and upon which agglomenates mightform to interfere with the fiber depositingzproeess:or'toprovideclumps-which drop onto the fabrictandconstitutean impurity therein.

Various meansfor the adjustment of the angular relation ,of the.air..inlets.may .beprovided. As .illustratedwin Figure 1, one suchmeans includes an arm 21 which engages the nozzle 22 outwardly of thehousing and is pivoted at one end, as at 23, upon rocker arm 24 which isadapted to be secured in a vertical angle of adjustment by the screw andnut means 25 illustrated.

'Further-toiassist injthe smoothness ofoperationof thefibendepositinghead and the introduction offibers therein, a bafileplate 30 is provided of curvilinear construction which issecured .to theinner wall.of the housinginadvance. of the inlet openingto-provide'a'curvilinear wall therein which terminates ata levelbelowthe inletopening so as to deflect the circulating air streamheyond theinlet opening 'during=circulating"movements. The effect of suchdeflection of the. air-stream'by the baffle 30 causes a negativepressure to exist at the inlet opening with the result that the fibersfed into the opening through the feed chute are positively drawn intothe-housingand turbulence which ordinarily might exist in the feedopeningis thus substantially. completely-eliminated.

i It will bexunderstood that furtherchanges may be made in' the. detailsof construction, arrangement and operation without departing from the:spirit of the invention, -'-espe- .ciallyasdefinedin the followingclaims.

We claim:

1.. Apparatus for the air: deposition of dry fibers in'the manufacture.of :fibrous structures comprising '-a substan- .tially "cylindricalhousing having an' inlet -'-in 1 one *portion throughzwhich fibers-arefed: into "the-housing; arr-outlet in anotherportion v which :forms -aforaminous separating .wall through iwhich fibers -are=able 'to pass, acollecting wall spaced at short-distance from theseparating-wallhaving'foramens therein dimensioned to prevent passage of fibers, .meansfor feeding-dry' fibers through-the inlet into the housing andazplurality= of air:n0z'zles in the housing through which streams of airat high velocity are-directed into therhousing,'zsome'of said nozzlesbeing posit-ionedto directnstreamssof airtangentially into thehousing,others of saidznozzlesi'being positioned to direct theirstrearnsof air radially into the'housingwhereby the'airrand contained fibersrare caused towc'irculate rapidly about the housing in onedirectionsasaa composite stream having a substantially uniform.distribution of the "fibers-entrained therein for passage with the air:through the separating wall to i the collecting wall.

'2. 'Apparatus for the-air deposition of'dryfibers in the manufacture offibrous=structures comprising a substantiallycylindricalihousing'havinga fiber i-r'rlet-in one portion: throughwhich; fibers are fed-into the'housing, an outlet in another portionWhich-forms -a-foraminous separating wall 'throughwhichfibers are ableto=pass,-'acollectingwall spaced a :short distance from theseparatingwall having foramens therein dimensioned to prevent passage ,offibers,means forfeeding dryifibers through the-.inletiinto the housingpan'daplurality of'air inlets'in the housing through which-streams of air athigh velo'city are directed into =the' 'housing, .some of saidair'in-lets being positioned to directtheir streams of'air tangentiallyinto the housing,others ofsaidair=inlets being positionedtodirecttheir:streams ofair radially into the housing,uwhile still othersare positioned to direct their streams of air into the housing+at anglesbetween'tangential and radial whereby: the: air and entrained fibers arecaused -.to circulate as a.composite-'stream rapidly about thehousing-.and:entrain theifiberstherein in uniform distribution andmaintain separation so .that aesmall portion of the air i and ,fiberscontained :within the iuhousing =will pass together through theseparating wall tothe collecting wall.

'3. Apparatus :for the air deposition of-dry fibers in the, manufactureof fibrous structures :zcornprising a 'substantiallyzcylindricalhousing. having: aniinlet in oneaportion through which fibers are fedinto the housinggan autlet sin anothenportion which "forms a 'foraminousseparating wall through which fibers are able to pass, a collecting wallspaced a short distance from the separating Wall having foramens thereindimensioned to prevent passage of fibers, means for feeding dry fibersthrough the inlet into the housing at a rate to maintain a load offibers within the housing, a plurality of air nozzles arrangedtransversely across the housing through which streams of air at highvelocity are directed into the housing, most of said air nozzles beingpositioned to direct their streams of air tangentially into the housing,others of said nozzles being positioned to direct their streams of airradially into the housing, while still others are positioned to directtheir streams of air into the housing at an angle between tangential andradial whereby the air and entrained fibers are caused to circulaterapidly as a composite stream about the housing in one direction and thefibers within the housing entrained in the air stream in uniformdistribution and in a manner to maintain substantial sepaartion forpassage with the air through the separating wall to the collecting wall.

References Cited in the file of this patent UNITED STATES PATENTS2,317,895 Drill Apr. 27, 1943 2,589,008 Lannan Mar. 11, 1952 2,641,028Steele June 9, 1953 2,651,812 Black Sept. 15, 1953

1. APPARATUS FOR THE AIR DEPOSITION OF DRY FIBERS IN THE MANUFACTURE OFFIBROUS STRUCTURE COMPRISING A SUBSTANTIALLY CYLINDRICAL HOUSING HAVINGAN INLET IN ONE PORTION THROUGH WHICH FIBERS ARE FED INTO THE HOUSING,AN OUTLET IN ANOTHER PORTION WHICH FORMS A FORAMINOUS SEPERATING WALLTHROUGH WHICH FIBERS ARE ABLE TO PASS, A COLLECTING WALL SPACED A SHORTDISTANCE FROM THE SEPARATING WALL HAVING FORAMENS THEREIN DIMENSIONED TOPREVENT PASSAGE OF FIBERS, MEANS FOR FEEDING DRY FIBERS THROUGH THEINLET INTO THE HOUSING AND A PLURALITY OF AIR NOZZLES IN THE HOUSINGTHROUGH WHICH STREAMS OF AIR AT HIGH VELOCITY ARE DIRECTED INTO THEHOUSING, SOME OF SAID NOZZLES BEING POSITIONED TO DIRECT STREAMS OF AIRTANGENTIALLY INTO THE HOUSING, OTHERS OF SAID NOZZLES BEING POSITIONEDTO DIRECT THEIR STREAMS OF AIR RADIALLY INTO THE HOUSING WHEREBY THE AIRAND CONTAINED FIBERS ARE CAUSED TO CIRCULATE RAPIDLY ABOUT THE HOUSINGIN ONE DIRECTION AS A COMPOSITE STRAM HAVING A SUBSTANTIALLY UNIFORMDISTRIBUTION OF THE FIBERS ENTRAINED THEREIN FOR PASSAGE WITH THE AIRTHROUGH THE SEPERATING WALL TO THE COLLECTING WALL.